Electrostatic chuck

ABSTRACT

An electrostatic chuck includes a base plate and a ceramic dielectric substrate. The ceramic dielectric substrate has a first major surface. The first major surface includes at least a first region and a second region. At least one first gas introduction hole connected to at least one of multiple first grooves. The first grooves include a first boundary groove, and at least one first in-region groove. Multiple second grooves and at least one second gas introduction hole are provided in the second region. The second grooves are include a second boundary groove extending along the first boundary and are provided to be most proximal to the first boundary. A groove end portion-end portion distance between the first boundary groove and the second boundary groove is smaller than a groove end portion-end portion distance between the first boundary groove and the first in-region groove.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/723,064, filed Dec. 20, 2019, which is based upon and claimsthe benefit of priority from Japanese Patent Application No.2018-239376, filed on Dec. 21, 2018, No. 2018-239382, filed on Dec. 21,2018, No. 2018-239418, filed on Dec. 21, 2018, No. 2019-162964, filed onSep. 6, 2019, No. 2019-162973, filed on Sep. 6, 2019, No. 2019-162997,filed on Sep. 6, 2019, No. 2019-224420, filed on Dec. 12, 2019, No.2019-224452, filed on Dec. 12, 2019, and No. 2019-220213, filed on Dec.5, 2019; the entire contents of which are incorporated herein byreference.

FIELD

An aspect of the invention relates to an electrostatic chuck.

BACKGROUND

An electrostatic chuck includes, for example, a ceramic dielectricsubstrate made of alumina or the like, and an electrode provided in theinterior of the ceramic dielectric substrate. An electrostatic force isgenerated when electrical power is applied to the electrode. Theelectrostatic chuck attracts and holds an object such as a silicon waferor the like by the generated electrostatic force. In such anelectrostatic chuck, the temperature of the object is controlled bycausing an inert gas (hereinbelow, called simply the gas) such as helium(He) or the like to flow between the front surface of the ceramicdielectric substrate and the back surface of the object.

For example, in an apparatus such as a CVD (Chemical Vapor Deposition)apparatus, a sputtering apparatus, an ion implantation apparatus, anetching apparatus, or the like which processes a substrate, there arecases where the temperature of the substrate increases in theprocessing. Therefore, in an electrostatic chuck used in such anapparatus, heat dissipation of the substrate is realized by causing thegas to flow between the ceramic dielectric substrate and the substrateand by causing the gas to contact the substrate.

Also, a temperature distribution occurs in the surface of the object inthe processing. In such a case, the temperature of the object can bereduced if the pressure of the gas is increased because the heatdissipation amount from the object increases. Therefore, the in-planetemperature of the object is controlled by subdividing the surface ofthe ceramic dielectric substrate on the object side into multipleregions and by changing the pressure of the gas in the multiple regions.

For example, technology has been proposed in which sealing rings areprovided between the regions to control the pressure of the gas in eachregion.

In such a case, it is favorable for the regions to be partitionedairtightly by the sealing rings to control the pressure of the gas ineach region. However, doing so causes particles occurring in waferpatterning processes to collect easily at the sealing ring portions; andthere is a risk of discrepancies in which defects occur at suchportions.

Technology also has been proposed in which the pressure of the gas ineach region is controlled by providing a slight gap between the objectand the top portion of the sealing ring.

In such a case as well, the problem of the particles collecting easilyat the sealing ring portions has not been solved.

Therefore, it is desirable to develop technology in which the depositionof the particles at the sealing ring portions can be suppressed whileeffectively controlling the pressure of the gas in each region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view for illustrating anelectrostatic chuck according to the embodiment.

FIG. 2 is a schematic cross-sectional view for illustrating a ceramicdielectric substrate, an electrode, and a first porous portion.

FIG. 3A is a schematic cross-sectional view for illustrating thearrangement of the grooves and the arrangement of the gas introductionholes according to a comparative example. FIG. 3B is a schematiccross-sectional view for illustrating an example of the arrangement ofthe grooves and the arrangement of the gas introduction holes accordingto the embodiment.

FIG. 4 is a graph of the pressure in the regions and the pressure at theregion-region boundaries determined by simulation.

FIG. 5 is a graph for illustrating the effect of the boundary-groovespacing.

FIG. 6A is a graph for illustrating the effect of the boundary-groovespacing using the “slope deviation rate.” FIG. 6B is a graph fordescribing the “slope deviation rate.”

FIG. 7 is an enlarged view of portion H of FIG. 6A.

FIG. 8 is a graph for illustrating the effect of the number of secondgrooves (the grooves 14 a and 14 b).

FIG. 9A is a schematic cross-sectional view for illustrating thearrangement of the gas introduction holes. FIG. 9B is a schematiccross-sectional view for illustrating the arrangement of the gasintroduction holes according to another embodiment.

FIGS. 10A and 10B are graphs of the pressure in the regions and thepressure at the region-region boundary determined by simulation.

FIG. 11 is a schematic plan view of a ceramic dielectric substrateaccording to another embodiment.

FIG. 12A is a schematic plan view for illustrating the arrangement ofthe grooves according to a comparative example.

FIG. 12B is a schematic plan view for illustrating the arrangement ofthe grooves.

FIG. 13 is a graph for illustrating the pressure change at the center ofthe substrate.

FIGS. 14A to 14C are schematic views for illustrating the form of agroove 14 c.

FIG. 15 is a schematic plan view of a ceramic dielectric substrateaccording to another embodiment.

FIG. 16 is a schematic view for illustrating a processing apparatusaccording to the embodiment.

DETAILED DESCRIPTION

A first invention is an electrostatic chuck including a base plate and aceramic dielectric substrate; the ceramic dielectric substrate isprovided on the base plate and has a first major surface exposedexternally; the first major surface includes at least a first region (aregion 101), and a second region (a region 102) adjacent to the firstregion; multiple first grooves (grooves 14 a and 14 b) and at least onefirst gas introduction hole (gas introduction hole 15) connected to atleast one of the multiple first grooves are provided in the first regionof the first major surface; the multiple first grooves include a firstboundary groove (the groove 14 a) extending along a first boundary (aboundary 102 a) and being provided to be most proximal to the firstboundary, and at least one first in-region groove (groove 14 b)different from the first boundary groove; the first boundary is betweenthe first region and the second region; multiple second grooves (thegrooves 14 a and 14 b) and at least one second gas introduction hole(gas introduction hole 15) connected to at least one of the multiplesecond grooves are provided in the second region of the first majorsurface; the multiple second grooves include a second boundary groove(the groove 14 a) extending along the first boundary and being providedto be most proximal to the first boundary; and a groove end portion-endportion distance (L1) between the first boundary groove and the secondboundary groove is smaller than a groove end portion-end portiondistance (L2) between the first boundary groove and the first in-regiongroove adjacent to the first boundary groove.

The electrostatic chuck does not include a sealing ring conventionallyarranged between the regions to control the pressure of the gas in eachregion. In other words, when an object W is placed, one enclosed spaceis formed between the object W and the ceramic dielectric substrate (thefirst region and the second region). Therefore, the problem of particlescollecting at the sealing ring portions can be solved. On the otherhand, if the sealing rings simply are not provided, the splitting of thegas pressure for each region is difficult; and the gas pressurecontrollability undesirably degrades. Therefore, in the invention, notonly are the sealing rings eliminated, but also a contrivance is made sothat the groove end portion-end portion distance between a firstboundary groove and a second boundary groove is shorter than the grooveend portion-end portion distance between the first boundary groove and afirst in-region groove adjacent to the first boundary groove.

Also, according to the electrostatic chuck, the region where theintended gas pressure is realized can be large because the region wherethe pressure of the gas changes at the vicinity of the region-regionboundary can be small. Therefore, the pressure of the gas in each regioncan be effectively controlled while solving the problem of thedeposition of the particles.

A second invention is the electrostatic chuck of the first invention,wherein the groove end portion-end portion distance between the firstboundary groove and the second boundary groove is shorter than a grooveend portion-end portion distance between the first in-region grooves.

According to the electrostatic chuck, the pressure of the gas in eachregion can be more effectively controlled.

A third invention is the electrostatic chuck of the first invention,wherein when projected onto a plane perpendicular to a first direction,at least a portion of the first gas introduction hole overlaps the firstboundary groove; and the first direction is from the base plate towardthe ceramic dielectric substrate.

The electrostatic chuck has excellent gas controllability because thefirst boundary groove and the first gas introduction hole are directlylinked. Therefore, the region where the pressure of the gas changes atthe vicinity of the region-region boundary can be smaller.

A fourth invention is the electrostatic chuck of the first invention,wherein when projected onto a plane perpendicular to a first direction,at least a portion of the second gas introduction hole overlaps thesecond boundary groove; and the first direction is from the base platetoward the ceramic dielectric substrate.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A fifth invention is the electrostatic chuck of the first invention,wherein an angle between the first boundary and a line connecting acenter of the first gas introduction hole and a center of the second gasintroduction hole is less than 90°.

According to the electrostatic chuck, it is possible for the boundarygrooves to be more proximal to each other; and the region where thepressure of the gas changes can be small. Therefore, the region wherethe intended gas pressure is realized can be large.

A sixth invention is the electrostatic chuck of the first invention,wherein an angle between the first boundary and a line connecting acenter of the first gas introduction hole and a center of the second gasintroduction hole is 90°.

According to the electrostatic chuck, the pressure in each region ismaintained more easily at the target pressure.

A seventh invention is the electrostatic chuck of the first invention,wherein the first major surface further has a lift pin hole provided inthe first major surface; and a distance between the lift pin hole andthe first boundary groove is greater than a distance between the liftpin hole and the first in-region groove most proximal to the lift pinhole.

According to the electrostatic chuck, the pressure change inside theregion can be reduced.

An eighth invention is the electrostatic chuck of the first invention,wherein the first major surface includes at least the first region, thesecond region positioned outward of the first region, a third region (aregion 103) adjacent to the second region and positioned outward of thesecond region; the multiple second grooves include a second outerboundary groove (the groove 14 a) extending along a second boundary andbeing provided to be most proximal to the second boundary; the secondboundary is between the second region and the third region; a thirdboundary groove (the groove 14 a) is provided in the third region, isprovided to be adjacent to the second boundary, and extends along thesecond boundary; and a groove end portion-end portion distance (L4)between the second outer boundary groove and the third boundary grooveis larger than the groove end portion-end portion distance (L1) betweenthe first boundary groove and the second boundary groove.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A ninth invention is the electrostatic chuck of the eighth invention,further including an outer seal provided to surround a peripheral edgeof the first major surface; at least a portion of the outer seal isconfigured to contact a chucking object; in a second directionorthogonal to a first direction, a distance between the second boundaryand the outer seal is shorter than a distance between the first boundaryand the second boundary; and the first direction is from the base platetoward the ceramic dielectric substrate.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A tenth invention is the electrostatic chuck of the fourth invention,wherein the first gas introduction hole is provided to be configured tosupply a gas to the first boundary groove, and at least two first gasintroduction holes are provided.

According to the electrostatic chuck, the gas is certainly supplied tothe first boundary groove extending along the first boundary (boundary102 a).

An eleventh invention is the electrostatic chuck of the tenth invention,wherein the second gas introduction hole is provided to be configured tosupply the gas to the second boundary groove, and at least two secondgas introduction holes are provided.

According to the electrostatic chuck, the gas is certainly supplied tothe second boundary groove extending along the first boundary (boundary102 a).

A twelfth invention is an electrostatic chuck including a base plate anda ceramic dielectric substrate; the ceramic dielectric substrate isprovided on the base plate and has a first major surface exposedexternally; the first major surface includes at least a first region(the region 101), and a second region (the region 102) adjacent to thefirst region; multiple first grooves (the grooves 14 a and 14 b) and atleast one first gas introduction hole (gas introduction hole 15)connected to at least one of the multiple first grooves are provided inthe first region of the first major surface; the multiple first groovesinclude a first boundary groove (the groove 14 a) extending along afirst boundary (the boundary 102 a) and being provided to be mostproximal to the first boundary, and at least one first in-region groove(the groove 14 b) different from the first boundary groove; the firstboundary is between the first region and the second region; multiplesecond grooves (the grooves 14 a and 14 b) and at least one second gasintroduction hole (gas introduction hole 15) connected to at least oneof the multiple second grooves are provided in the second region of thefirst major surface; the multiple second grooves include a secondboundary groove (the groove 14 a) extending along the first boundary andbeing provided to be most proximal to the first boundary; and a boundarygroove occupancy ratio in a first area (an area C1) having a prescribedunit area and including the first boundary, the first boundary groove,and the second boundary groove is larger than an in-region grooveoccupancy ratio in a second area (areas D and D1) having the sameconfiguration and the same dimensions as the first area and includingthe first in-region groove.

The electrostatic chuck does not include a sealing ring conventionallyarranged between the regions to control the pressure of the gas in eachregion. In other words, when the object W is placed, one enclosed spaceis formed between the object W and the ceramic dielectric substrate (thefirst region and the second region). Therefore, the problem of theparticles collecting at the sealing ring portions can be solved. On theother hand, if the sealing rings simply are not provided, the splittingof the gas pressure for each region is difficult; and the gas pressurecontrollability undesirably degrades. Therefore, in the invention, notonly are the sealing rings eliminated, but also a contrivance is made sothat the groove end portion-end portion distance between the firstboundary groove and a second boundary groove is shorter than the grooveend portion-end portion distance between the first boundary groove andthe first in-region groove adjacent to the first boundary groove.

Also, according to the electrostatic chuck, the region where theintended gas pressure is realized can be large because the region wherethe pressure of the gas changes at the vicinity of the region-regionboundary can be small. Therefore, the pressure of the gas in each regioncan be effectively controlled while solving the problem of thedeposition of the particles.

A thirteenth invention is the electrostatic chuck of the twelfthinvention, wherein a groove end portion-end portion distance between thefirst boundary groove and the second boundary groove is shorter than agroove end portion-end portion distance between the first in-regiongrooves.

According to the electrostatic chuck, the pressure of the gas in eachregion can be more effectively controlled.

A fourteenth invention is the electrostatic chuck of the twelfthinvention, wherein when projected onto a plane perpendicular to a firstdirection, at least a portion of the first gas introduction holeoverlaps the first boundary groove; and the first direction is from thebase plate toward the ceramic dielectric substrate.

The electrostatic chuck has excellent gas controllability because thefirst boundary groove and the first gas introduction hole are directlylinked. Therefore, the region where the pressure of the gas changes atthe vicinity of the region-region boundary can be smaller.

A fifteenth invention is the electrostatic chuck of any one of thetwelfth invention, wherein when projected onto a plane perpendicular toa first direction, at least a portion of the second gas introductionhole overlaps the second boundary groove; and the first direction isfrom the base plate toward the ceramic dielectric substrate.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A sixteenth invention is the electrostatic chuck of any one of thetwelfth invention, wherein an angle between the first boundary and aline connecting a center of the first gas introduction hole and a centerof the second gas introduction hole is less than 90°.

According to the electrostatic chuck, it is possible for the boundarygrooves to be more proximal to each other; and the region where thepressure of the gas changes can be small. Therefore, the region wherethe intended gas pressure is realized can be large.

A seventeenth invention is the electrostatic chuck of any one of thetwelfth invention, wherein an angle between the first boundary and aline connecting a center of the first gas introduction hole and a centerof the second gas introduction hole is 90°.

According to the electrostatic chuck, the pressure in each region ismaintained more easily at the target pressure.

An eighteenth invention is the electrostatic chuck of any one of thetwelfth invention, wherein the first major surface further has a liftpin hole provided in the first major surface; and a distance between thelift pin hole and the first boundary groove is greater than a distancebetween the lift pin hole and the first in-region groove most proximalto the lift pin hole.

According to the electrostatic chuck, the pressure change inside theregion can be reduced.

A nineteenth invention is the electrostatic chuck of any one of thetwelfth invention, wherein the first major surface includes at least thefirst region, the second region positioned outward of the first region,and a third region (the region 103) adjacent to the second region andpositioned outward of the second region; the multiple second groovesinclude a second outer boundary groove (the groove 14 a) extending alonga second boundary and being provided to be most proximal to the secondboundary; the second boundary is between the second region and the thirdregion; a third boundary groove (the groove 14 a) is provided in thethird region, is provided to be adjacent to the second boundary, andextends along the second boundary; and a boundary groove occupancy ratioin a third area (an area C2) having the prescribed unit area andincluding the second boundary, the second boundary groove, and the thirdboundary groove is larger than the in-region groove occupancy ratio inthe first area (the area C1).

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

An twentieth invention is the electrostatic chuck of the nineteenthinvention, further including an outer seal provided to surround aperipheral edge of the first major surface; at least a portion of theouter seal is configured to contact a chucking object; in a seconddirection orthogonal to a first direction, a distance between the secondboundary and the outer seal is shorter than a distance between the firstboundary and the second boundary; and the first direction is from thebase plate toward the ceramic dielectric substrate.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A twenty-first invention an electrostatic chuck including a base plateand a ceramic dielectric substrate; the ceramic dielectric substrate isprovided on the base plate and has a first major surface exposedexternally; the first major surface includes at least a first region(the region 101), and a second region (the region 102) adjacent to thefirst region; multiple first grooves (the grooves 14 a and 14 b) and atleast one first gas introduction hole (gas introduction hole 15)connected to at least one of the multiple first grooves are provided inthe first region of the first major surface; the multiple first groovesinclude a first boundary groove (the groove 14 a) extending along afirst boundary (the boundary 102 a) and being provided to be mostproximal to the first boundary; the first boundary is between the firstregion and the second region; multiple second grooves (the grooves 14 aand 14 b), and at least one second gas introduction hole (gasintroduction hole 15) connected to at least one of the multiple secondgrooves are provided in the second region of the first major surface;the multiple second grooves include a second boundary groove extendingalong the first boundary and being provided to be most proximal to thefirst boundary; and a groove end portion-end portion distance betweenthe first boundary groove and the second boundary groove (the groove 14a) is greater than 0 mm but not more than 60 mm.

The electrostatic chuck does not include a sealing ring conventionallyarranged between the regions to control the pressure of the gas in eachregion. In other words, when the object W is placed, one enclosed spaceis formed between the object W and the ceramic dielectric substrate (thefirst region and the second region). Therefore, the problem of theparticles collecting at the sealing ring portions can be solved. On theother hand, if the sealing rings simply are not provided, the splittingof the gas pressure for each region is difficult; and the gas pressurecontrollability undesirably degrades. Therefore, in the invention, notonly are the sealing rings eliminated, but also a contrivance is made sothat the groove end portion-end portion distance between the firstboundary groove and the second boundary groove is greater than 0 mm butnot more than 60 mm.

Also, according to the electrostatic chuck, the region where theintended gas pressure is realized can be large because the region wherethe pressure of the gas changes at the vicinity of the region-regionboundary can be small. Therefore, the pressure of the gas in each regioncan be effectively controlled while solving the problem of thedeposition of the particles.

A twenty-second invention is the electrostatic chuck of the twenty-firstinvention, wherein the groove end portion-end portion distance betweenthe first boundary groove and the second boundary groove is greater than0 mm but not more than 20 mm.

According to the electrostatic chuck, the pressure of the gas in eachregion can be more effectively controlled.

A twenty-third invention is the electrostatic chuck of the twenty-firstinvention, wherein when projected onto a plane perpendicular to a firstdirection, at least a portion of the first gas introduction holeoverlaps the first boundary groove; and the first direction is from thebase plate toward the ceramic dielectric substrate.

The electrostatic chuck has excellent gas controllability because thefirst boundary groove and the first gas introduction hole are directlylinked. Therefore, the region where the pressure of the gas changes atthe vicinity of the region-region boundary can be smaller.

A twenty-fourth invention is the electrostatic chuck of any one of thetwenty-first invention, wherein when projected onto a planeperpendicular to a first direction, at least a portion of the second gasintroduction hole overlaps the second boundary groove; and the firstdirection is from the base plate toward the ceramic dielectricsubstrate.

According to the electrostatic chuck, the region where the pressure ofthe gas changes at the vicinity of the region-region boundary can besmaller.

A twenty-fifth invention is the electrostatic chuck of any one of thetwenty-first invention, wherein an angle between the first boundary anda line connecting a center of the first gas introduction hole and acenter of the second gas introduction hole is less than 90°.

According to the electrostatic chuck, it is possible for the boundarygrooves to be more proximal to each other; and the region where thepressure of the gas changes can be small. Therefore, the region wherethe intended gas pressure is realized can be large.

A twenty-sixth invention is the electrostatic chuck of any one of thetwenty-first invention, wherein an angle between the first boundary anda line connecting a center of the first gas introduction hole and acenter of the second gas introduction hole is 90°.

According to the electrostatic chuck, the pressure in each region ismaintained more easily at the target pressure.

A twenty-seventh invention is the electrostatic chuck of any one of thetwenty-first invention, wherein the multiple first grooves furtherinclude at least one first in-region groove (groove 14 b) different fromthe first boundary groove; the first major surface has a lift pin holeprovided in the first major surface; and a distance between the lift pinhole and the first boundary groove is greater than a distance betweenthe lift pin hole and the first in-region groove most proximal to thelift pin hole.

According to the electrostatic chuck, the pressure change inside theregion can be reduced.

Embodiments of the invention will now be described with reference to thedrawings. Similar components in the drawings are marked with the samereference numerals; and a detailed description is omitted asappropriate.

In each drawing, a direction from a base plate 50 toward a ceramicdielectric substrate 11 is taken as a Z-direction; one directionsubstantially orthogonal to the Z-direction is taken as a Y-direction;and a direction substantially orthogonal to the Z-direction and theY-direction is taken as an X-direction.

Electrostatic Chuck

FIG. 1 is a schematic cross-sectional view for illustrating anelectrostatic chuck 1 according to the embodiment.

FIG. 2 is a schematic cross-sectional view for illustrating the ceramicdielectric substrate 11, an electrode 12, and a first porous portion 90.

As shown in FIG. 1, the ceramic dielectric substrate 11, the electrode12, the first porous portion 90, the base plate 50, and a second porousportion 70 can be provided in the electrostatic chuck 1.

As shown in FIG. 1 and FIG. 2, for example, the ceramic dielectricsubstrate 11 can be a flat-plate shaped member including a sinteredceramic. For example, the ceramic dielectric substrate 11 can includealuminum oxide (Al₂O₃). For example, the ceramic dielectric substrate 11can be formed using high-purity aluminum oxide. The concentration ofaluminum oxide in the ceramic dielectric substrate 11 can be, forexample, not less than 99 atomic percent (atomic %) and not more than100 atomic %. The plasma resistance of the ceramic dielectric substrate11 can be improved by using high-purity aluminum oxide. The porosity ofthe ceramic dielectric substrate 11 can be, for example, 1% or less. Thedensity of the ceramic dielectric substrate 11 can be, for example, 4.2g/cm³.

The ceramic dielectric substrate 11 has a first major surface 11 a wherethe chucking object W is placed, and a second major surface 11 b on theside opposite to the first major surface 11 a. The first major surface11 a is a surface of the electrostatic chuck 1 which is exposedexternally. The object W can be, for example, a semiconductor substratesuch as a silicon wafer or the like, a glass substrate, etc.

Multiple dots 13 are provided at the first major surface 11 a of theceramic dielectric substrate 11. The object W is placed on multiple dots13 and supported by the multiple dots 13. By providing the multiple dots13, a space is formed between the first major surface 11 a and the backsurface of the object W placed on the electrostatic chuck 1. Forexample, particles that adhere to the object W can be maintained in afavorable state by appropriately selecting the height and the number ofthe dots 13, the surface area ratio and the configuration of the dots13, etc. For example, the heights (the dimensions in the Z-direction) ofthe multiple dots 13 can be set to be not less than 1 μm and not morethan 100 μm, favorably not less than 1 μm and not more than 30 μm, andmore favorably not less than 5 μm and not more than 15 μm.

The multiple grooves 14 a and 14 b are provided in the first majorsurface 11 a of the ceramic dielectric substrate 11. The multiplegrooves 14 a and 14 b are open toward the first major surface 11 a sideof the ceramic dielectric substrate 11. The width (the dimension in theX-direction or the Y-direction) of the groove 14 a can be set to, forexample, not less than 0.1 mm and not more than 2.0 mm, favorably notless than 0.1 mm and not more than 1.0 mm, and more favorably not lessthan 0.2 mm and not more than 0.5 mm. The depth (the dimension in theZ-direction) of the groove 14 a can be set to, for example, not lessthan 10 μm and not more than 300 μm, favorably not less than 10 μm andnot more than 200 μm, and more favorably not less than 50 μm and notmore than 150 μm. The width (the dimension in the X-direction or theY-direction) of the groove 14 b can be set to, for example, not lessthan 0.1 mm and not more than 1.0 mm. The depth (the dimension in theZ-direction) of the groove 14 b can be set to, for example, not lessthan 0.1 mm and not more than 2.0 mm, favorably not less than 0.1 mm andnot more than 1.0 mm, and more favorably not less than 0.2 mm and notmore than 0.5 mm.

Multiple gas introduction holes 15 are provided in the ceramicdielectric substrate 11. One end portion of each of the multiple gasintroduction holes 15 can be connected to the grooves 14 a. The otherend portion of each of the multiple gas introduction holes 15 can beconnected via the first porous portions 90 to gas supply channels 53described below. The gas introduction hole 15 is provided from thesecond major surface 11 b to the first major surface 11 a. In otherwords, the gas introduction hole 15 pierces through the ceramicdielectric substrate 11 and extends in the Z-direction between thesecond major surface 11 b side and the first major surface 11 a side.The diameter of the gas introduction hole 15 can be set to be, forexample, not less than 0.05 mm and not more than 0.5 mm.

Details relating to the multiple grooves 14 a and 14 b and the multiplegas introduction holes 15 are described below.

The electrode 12 is provided in the interior of the ceramic dielectricsubstrate 11. The electrode 12 is provided between the first majorsurface 11 a and the second major surface 11 b of the ceramic dielectricsubstrate 11.

For example, the electrode 12 can have a thin-film configuration alongthe first major surface 11 a and the second major surface 11 b of theceramic dielectric substrate 11. The electrode 12 is a chuckingelectrode for attracting and holding the object W. The electrode 12 maybe unipolar or bipolar. The electrode 12 illustrated in FIG. 1 isbipolar; and the electrode 12 that is provided has two poles in the sameplane.

A connector 20 is provided at the electrode 12. The electrode 12 and theconnector 20 can be formed from a conductive material such as a metal,etc. The end portion of the connector 20 on the side opposite to theelectrode 12 side can be exposed at the second major surface 11 b sideof the ceramic dielectric substrate 11. The connector 20 can be, forexample, a via (solid) or a via hole (hollow) conducting to theelectrode 12. The connector 20 may be a metal terminal connected by anappropriate method such as brazing, etc.

A power supply 210 is electrically connected to the electrode 12 via theconnector 20. A charge can be generated in the region of the electrode12 on the first major surface 11 a side by applying a prescribed voltageto the electrode 12. Therefore, the object W is held to the first majorsurface 11 a side of the ceramic dielectric substrate 11 by anelectrostatic force.

The first porous portion 90 is provided in the interior of the ceramicdielectric substrate 11. For example, the first porous portion 90 can beprovided at a position opposing the gas supply channel 53 between thebase plate 50 and the first major surface 11 a of the ceramic dielectricsubstrate 11 in the Z-direction. For example, the first porous portion90 can be provided at the gas introduction hole 15 of the ceramicdielectric substrate 11. For example, the first porous portion 90 isinserted into a portion of the gas introduction hole 15.

In the case of the first porous portion 90 illustrated in FIG. 1 andFIG. 2, the first porous portion 90 is provided at the portion of thegas introduction hole 15 at the second major surface 11 b side. One endportion of the first porous portion 90 is exposed at the second majorsurface 11 b of the ceramic dielectric substrate 11. The other endportion of the first porous portion 90 is positioned between the firstmajor surface 11 a and the second major surface 11 b. The other endportion of the first porous portion 90 may be exposed at the bottomsurface of the groove 14 a. Both end portions of the first porousportion 90 may be positioned between the first major surface 11 a andthe second major surface 11 b.

The material of the first porous portion 90 can be, for example, aninsulative ceramic. The first porous portion 90 includes, for example,at least one of aluminum oxide (Al₂O₃), titanium oxide (TiO₂), oryttrium oxide (Y₂O₃). Thus, the first porous portion 90 can have a highinsulation breakdown voltage and a high rigidity.

In such a case, the purity of the aluminum oxide of the ceramicdielectric substrate 11 can be set to be higher than the purity of thealuminum oxide of the first porous portion 90. Thus, the performancesuch as the plasma resistance, etc., of the electrostatic chuck 1 can beensured; and the mechanical strength of the first porous portion 90 canbe ensured. As an example, a trace amount of an additive is included inthe first porous portion 90; thereby, the sintering of the first porousportion 90 is promoted; and it is possible to control the pores and/orensure the mechanical strength.

For example, the purity of the ceramic such as aluminum oxide, etc., canbe measured by X-ray fluorescence analysis, ICP-AES (Inductively CoupledPlasma-Atomic Emission Spectrometry), etc.

As shown in FIG. 1, for example, the base plate 50 supports the ceramicdielectric substrate 11. For example, the ceramic dielectric substrate11 can be bonded onto the base plate 50. The bonding agent can be, forexample, a silicone bonding agent, etc.

For example, the base plate 50 is made of a metal. For example, the baseplate 50 is divided into an upper portion 50 a and a lower portion 50 bmade of aluminum; and a connection channel 55 is provided between theupper portion 50 a and the lower portion 50 b. One end of the connectionchannel 55 is connected to an input channel 51; and the other end of theconnection channel 55 is connected to an output channel 52.

The base plate 50 also performs the role of the temperature adjustmentof the dielectric substrate 11. For example, when cooling the dielectricsubstrate 11, a cooling medium is caused to inflow through the inputchannel 51, pass through the connection channel 55, and outflow from theoutput channel 52. Thereby, the heat of the base plate 50 is absorbed bythe cooling medium; and the ceramic dielectric substrate 11 which ismounted on the base plate 50 can be cooled. When maintaining thetemperature of the dielectric substrate 11, it is also possible to causea heat-retaining medium to inflow into the connection channel 55. If thetemperature of the dielectric substrate 11 can be controlled, it is easyto control the temperature of the object W held by the dielectricsubstrate 11.

A gas is supplied to the multiple grooves 14 a and 14 b. The temperatureof the object W is controlled by the supplied gas contacting the objectW. In such a case, as long as the temperature of the base plate 50 canbe controlled, the range of the temperature control by the gas suppliedto the grooves 14 a and 14 b can be small. For example, the temperatureof the object W can be roughly controlled by the base plate 50; and thetemperature of the object W can be precisely controlled by the gassupplied to the grooves 14 a and 14 b.

Multiple gas supply channels 53 can be provided in the base plate 50.The gas supply channel 53 can be provided to pierce through the baseplate 50. The gas supply channel 53 may not pierce through the baseplate 50, and may be provided to reach the ceramic dielectric substrate11 side by branching partway through other gas supply channels 53.

The gas supply channel 53 is connected to the gas introduction hole 15.In other words, the gas that inflows into the gas supply channel 53inflows into the gas introduction hole 15 after passing through the gassupply channel 53.

The gas that inflows into the gas introduction hole 15 inflows into thegroove 14 a to which the gas introduction hole 15 is connected afterpassing through the gas introduction hole 15. Thereby, the object W canbe directly cooled by the gas.

The second porous portion 70 can be provided between the first porousportion 90 and the gas supply channel 53 in the Z-direction. Forexample, the second porous portion 70 is fitted into the end surface ofthe base plate 50 on the ceramic dielectric substrate 11 side. As shownin FIG. 1, for example, a countersink portion 53 a can be provided inthe end surface of the base plate 50 on the ceramic dielectric substrate11 side; and the second porous portion 70 can be fitted into thecountersink portion 53 a. The countersink portion 53 a is connected tothe gas supply channel 53. The second porous portion 70 can be providedto oppose the first porous portion 90.

The multiple grooves 14 a and 14 b and the multiple gas introductionholes 15 will now be described further. As described above, thetemperature of the object W can be controlled by the gas supplied to themultiple grooves 14 a and 14 b. There are cases where a temperaturedistribution occurs in the surface of the object W in the processing ofthe object W. For example, there are cases where a region where thetemperature is low and/or a region where the temperature is high occurin the surface of the object W. In such a case, by setting the pressureof the gas contacting the region where the temperature is high to behigher than the pressure of the gas contacting the region where thetemperature is low, the heat dissipation amount is high in the regionwhere the temperature is high; therefore, the temperature of the objectW can be controlled; and the occurrence of the temperature distributionin the surface of the object W can be suppressed.

For example, the in-plane temperature of the object W can be controlledby subdividing the first major surface 11 a side of the ceramicdielectric substrate 11 into multiple regions and by changing thepressure of the gas supplied to the multiple regions. To control thepressure of the gas in each region in such a case, there are examples inwhich sealing rings are provided between the regions to partition theregions. In such an example, the top portion of the sealing ringcontacts the surface of the object W at the first major surface 11 aside. Thus, the flow of the gas between the regions can be substantiallyeliminated; therefore, the pressure of the gas in each region can beeffectively controlled.

However, if sealing rings are provided, particles that occur in thewafer patterning processes collect easily at the sealing ring portions;and there is a risk of discrepancies in which defects occur at suchportions.

Therefore, in the invention, a contrivance is made for the arrangementof the grooves 14 a and 14 b without providing the sealing rings fordividing the regions. In other words, when the object W is placed, anenclosed space is formed between the object W and the ceramic dielectricsubstrate 11 (e.g., the region 101 and the region 102). According to theinvention, the pressure control inside the regions can be performedeffectively even without sealing rings.

In the invention, it is sufficient for the pressure of the gas in eachregion to be able to be effectively controlled substantially withoutproviding sealing rings; and it is acceptable for sealing rings to beprovided partially or locally. In other words, sealing rings may beprovided partially or locally as long as the effect of effectivelycontrolling the pressure of the gas in each region substantially withoutproviding sealing rings is provided.

FIG. 3A is a schematic cross-sectional view for illustrating thearrangement of grooves 14 and the arrangement of the gas introductionholes 15 according to a comparative example.

In FIG. 3A, the grooves 14 are provided at uniform spacing in theX-direction. In other words, a groove end portion-end portion distanceL23 is set to be the same along the X-direction.

In the specification, the groove end portion-end portion distance refersto the shortest distance for two adjacent grooves between the inner wallof one groove at the other groove side and the inner wall of the othergroove at the one groove side. In such a case, if the groove endportion-end portion distance of the two grooves changes, the shortestdistance can be taken as the groove end portion-end portion distance.

A region 100 a and a region 100 b 1 are adjacent in the X-direction; andthe region 100 a and a region 100 b 2 are adjacent in the X-direction.In FIG. 3A, the gas introduction holes 15 are connected to the twogrooves 14 provided with the boundary between the region 100 a and theregion 100 b 1 interposed.

The pressure of the gas supplied to the groove 14 provided in the region100 a is taken as P1; the pressure of the gas supplied to the groove 14provided in the region 100 b 1 is taken as P2; and the pressure of thegas supplied to the groove 14 provided in the region 100 b 2 is taken asP3.

FIG. 3B is a schematic cross-sectional view for illustrating an exampleof the arrangement of the grooves 14 a and 14 b and the arrangement ofthe gas introduction holes 15 according to the embodiment. The grooves14 a are boundary grooves provided with the boundary between differentregions interposed; and the grooves 14 b are in-region grooves otherthan the grooves 14 a provided inside the region.

In FIG. 3B, the groove end portion-end portion distance (theboundary-groove spacing) of the two grooves 14 a (the boundary grooves)provided with the boundary between the region 100 a and the region 100 b1 or the boundary between the region 100 a and the region 100 b 2interposed in the X-direction is taken as L21; and the groove endportion-end portion distance (the in-region groove spacing) between thegroove 14 a (the boundary groove) and the groove 14 b (the in-regiongroove) other than the grooves 14 a provided inside the region 100 aadjacent to the boundary groove 14 a is taken as L22. In such a case,L21<L22. The groove end portion-end portion distance between the groove14 a (the boundary groove) and the groove 14 b other than the grooves 14a provided inside the region 100 b 1 adjacent to the boundary groove 14a is taken as L24; and the groove end portion-end portion distancebetween the groove 14 a (the boundary groove) and the groove 14 b otherthan the grooves 14 a provided inside the region 100 b 2 also is takenas L24.

The pressure of the gas supplied via the gas introduction hole 15 to thegroove 14 a provided in the region 100 a is taken as P1; and thepressure of the gas supplied via the gas introduction hole 15 to thegroove 14 a provided in the region 100 b 1 is taken as P2.

FIG. 4 is a graph determined by simulation of the pressure in the region100 a, the pressures in the regions 100 b 1 and 100 b 2, the pressure atthe boundary between the region 100 a and the region 100 b 1, and thepressure at the boundary between the region 100 a and the region 100 b2. In the simulation, it is taken that the object W is supported by thedots 13 above the first major surface 11 a of the ceramic dielectricsubstrate 11.

A in FIG. 4 is an example using the arrangement of the grooves 14 andthe arrangement of the gas introduction holes 15 illustrated in FIG. 3Ain which the boundary-groove spacing and the in-region groove spacingare equal.

B in FIG. 4 is an example using the arrangement of the grooves 14 a andthe grooves 14 b and the arrangement of the gas introduction holes 15illustrated in FIG. 3B in which the boundary-groove spacing is smallerthan the in-region groove spacing. In either example, sealing rings arenot provided between the regions.

In the simulation, P1=3×P2; the groove end portion-end portion distanceL21 is set to 5 mm; the groove end portion-end portion distance L22 isset to 20 mm; and the groove end portion-end portion distance L23 is setto 15 mm. The dimension of the region 100 a in the X-direction is set to50 mm.

It can be seen from FIG. 4 that when the boundary-groove spacing and thein-region groove spacing are equal (the case of A), the region where thepressure of the gas changes is large at the vicinity of the boundarybetween the region 100 a and the region 100 b 1 and at the vicinity ofthe boundary between the region 100 a and the region 100 b 2.Conversely, when the boundary-groove spacing is smaller than thein-region groove spacing (the case of B), the region where the pressureof the gas changes at the vicinity of the boundary between the region100 a and the region 100 b 1 and at the vicinity of the boundary betweenthe region 100 a and the region 100 b 2 can be smaller than those of thecase of A. In other words, the region where the intended gas pressure isrealized can be increased in each of the region 100 a and the regions100 b 1 and 100 b 2; and the uniformity of the gas pressure inside theregions can be increased.

As described above, by adapting the arrangement of the grooves 14 a andthe grooves 14 b, the temperature of the object W can be controlled bythe pressure of the gas even without providing sealing rings between theregions. Therefore, if the uniformity of the gas pressure inside theregions can be increased, the temperature of the object W at theportions corresponding to the regions can be more effectivelycontrolled. Also, the occurrence of the in-plane distribution of thetemperature of the object W can be suppressed.

According to knowledge obtained by the inventors, it is favorable forthe gas introduction hole 15 to be connected to at least one of the twogrooves 14 a which are the boundary grooves provided with the boundaryinterposed because the effects described above can be obtained.

In such a case, the gap between the first major surface 11 a and theobject W has the height of the dots 13; therefore, the gas that issupplied to the groove 14 a to which the gas introduction hole 15 isconnected is supplied to the grooves 14 b and the other grooves 14 a viathe gap. In other words, in each region, the gas is supplied to thespace formed between the back surface of the object W and the firstmajor surface 11 a including the grooves 14 a and 14 b.

It is more favorable when the gas introduction holes 15 are connectedrespectively to the two grooves 14 a provided with the boundaryinterposed as illustrated in FIG. 3B because the change of the gaspressure at the region boundary can be more pronounced, and because thetemperature of the object W can be more effectively controlled. Also,the occurrence of the in-plane distribution of the temperature of theobject W can be suppressed more effectively.

FIG. 5 is a graph for illustrating the effect of the boundary-groovespacing.

The boundary-groove spacing of the horizontal axis is the groove endportion-end portion distance of two grooves (boundary grooves) providedwith the boundary between adjacent regions interposed. The effect of theboundary-groove spacing is the effect of the boundary-groove spacingitself and is applicable, for example, in the case of the distance L23illustrated in FIG. 3A or the distance L21 illustrated in FIG. 3B.

The deviation rate of the vertical axis illustrates how much the averagepressure in each region deviates from the set pressure (the intendedpressure). A large deviation rate shows that the difference between theintended pressure and the average pressure in each region is large.

In FIG. 5, for example, the deviation rate is determined by simulationby setting the pressure P1 in the region 100 a of FIGS. 3A and 3B to 20Torr (2666.4 Pa) and by setting the pressure P3 of the region 100 b 2 to60 Torr (7999.2 Pa).

It can be seen from FIG. 5 that the deviation rate increasessubstantially linearly when the boundary-groove spacing which is thegroove end portion-end portion distance of the boundary grooves isgreater than 0 mm but not more than 60 mm, and favorably greater than 0mm but not more than 20 mm. The deviation rate increases exponentiallywhen the boundary-groove spacing is greater than 60 mm. When theboundary-groove spacing is 60 mm or less, and favorably 20 mm or less,the increase of the deviation rate can be suppressed, which means thatthe average pressure in each region can approach the intended pressure.

As described above, the effect of the boundary-groove spacing is theeffect of the boundary-groove spacing itself; therefore, byappropriately combining the contrivance of the arrangement of thegrooves 14 a and 14 b described above, the arrangement of the gasintroduction holes 15 (the gas introduction holes 15 connected to theboundary grooves) described above, and the groove 14 c described below,the deposition of the particles at the sealing ring portions can besuppressed effectively while controlling the pressure of the gas in eachregion more effectively.

FIG. 6A is a graph for illustrating the effect of the boundary-groovespacing using the “slope deviation rate.”

FIG. 6B is a graph for describing the “slope deviation rate.”

FIG. 7 is an enlarged view of portion H of FIG. 6A.

If the pressure in the first region and the pressure in the secondregion are separated ideally, it is considered that the pressuredistribution at a first boundary between the first region and the secondregion has a straight-line distribution (changes linearly) as shown inFIG. 6B. Therefore, the effect of the boundary-groove spacing can beevaluated by arithmetically calculating the slope from the pressuredistribution between the regions determined by the analysis and bydetermining the deviation rate (the slope deviation rate) with respectto the ideal slope.

It can be seen from FIG. 6A that the slope deviation rate increasessubstantially linearly when the boundary-groove spacing which is thegroove end portion-end portion distance of the boundary grooves isgreater than 0 mm but not more than 60 mm. The slope deviation rateincreases exponentially when the boundary-groove spacing is greater than60 mm. When the boundary-groove spacing is 60 mm or less, the increaseof the slope deviation rate can be suppressed, which means that theaverage pressure in each region approaches the intended pressure.

It can be seen from FIG. 7 that when the boundary-groove spacing whichis the groove end portion-end portion distance of the boundary groovesis greater than 0 mm but not more than 20 mm, the slope deviation ratecan be more linear. When the boundary-groove spacing is 20 mm or less,the increase of the slope deviation rate can be suppressed further,which means that the average pressure in each region better approachesthe intended pressure.

FIG. 8 is a graph for illustrating the effect of the number of secondgrooves (the grooves 14 a and 14 b (the diametrical-direction grooves)).

It can be seen from FIG. 8 that the deviation rate can be reducedremarkably by providing at least two second grooves in the secondregion. In other words, the pressure of the first boundary (a boundary102 a) between the first region (the region 101) and the second region(the region 102) can approach the average value of the pressure in thefirst region and the pressure in the second region. Therefore, thepressure in each region is maintained more easily at the targetpressure.

According to knowledge obtained by the inventors, the effectsillustrated in FIG. 4 can be obtained if the boundary groove occupancyratio is larger than the in-region groove occupancy ratio. As usedherein, the term “groove occupancy ratio” means a portion of aprescribed unit area occupied by any groove(s) present in that area,divided by the prescribed unit area. In other words, if the boundarygroove occupancy ratio is larger than the in-region groove occupancyratio, the region where the pressure of the gas changes at the vicinityof the boundary can be small. Therefore, the temperature of the object Wcan be effectively controlled because the region where the intended gaspressure is realized can be large. Also, the occurrence of the in-planedistribution of the temperature of the object W can be suppressed.

FIG. 9A is a schematic cross-sectional view for illustrating thearrangement of the gas introduction holes 15.

In FIG. 9A, the region 100 a and the region 100 b 1 are adjacent in theX-direction; and the region 100 a and the region 100 b 2 are adjacent inthe X-direction. Also, two grooves 14 a (boundary grooves) are providedwith the boundary between the region 100 a and the region 100 b 1interposed in the X-direction; and two grooves 14 a (boundary grooves)are provided with the boundary between the region 100 a and the region100 b 2 interposed in the X-direction. Also, the grooves 14 b (thein-region grooves) are provided in the interior of the region 100 a andthe interiors of the regions 100 b 1 and 100 b 2. In the region 100 a,the gas introduction hole 15 is connected to the groove 14 a at theregion 100 b 1 side; but the gas introduction hole 15 is not connectedto the groove 14 a at the region 100 b 2 side. In the region 100 b 1,the gas introduction hole 15 is connected to the groove 14 a at theregion 100 a side. In the region 100 b 2, the gas introduction hole 15is connected to the groove 14 a at the region 100 a side. In otherwords, the gas introduction hole 15 is connected to only one groove 14 ain the region 100 a.

The pressure of the gas supplied to the groove 14 a provided in theregion 100 a is taken as P1; and the pressure of the gas supplied to thegrooves 14 a provided in the regions 100 b 1 and 100 b 2 is taken as P2

FIG. 9B is a schematic cross-sectional view for illustrating thearrangement of the gas introduction holes 15 according to anotherembodiment.

In FIG. 9B, the gas introduction holes 15 are connected to the groove 14a at the region 100 b 1 side and the groove 14 a at the region 100 b 2side in the region 100 a.

The pressure of the gas supplied to the grooves 14 a provided in theregion 100 a is taken as P1; and the pressure of the gas supplied to thegrooves 14 a provided in the regions 100 b 1 and 100 b 2 is taken as P2.

FIGS. 10A and 10B are graphs in which the pressure in the region 100 a,the pressures in the regions 100 b 1 and 100 b 2, the pressure at theboundary between the region 100 a and the region 100 b 1, and thepressure at the boundary between the region 100 a and the region 100 b 2are determined by simulation. In the simulation, the object W issupported by the dots 13 above the first major surface 11 a of theceramic dielectric substrate 11.

FIG. 10A is the case of FIG. 9A.

FIG. 10B is the case of FIG. 9B.

The dimension of the region 100 a in the X-direction is set to 50 mm;and P1=3×P2.

As shown in FIG. 9A, the gas introduction hole 15 is not connected tothe groove 14 a at the region 100 b 2 side of the region 100 a;therefore, it can be seen from FIG. 10A that the region where thepressure of the gas changes at the vicinity of the boundary is large.Therefore, the region where the intended gas pressure is realized issmall.

Conversely, the gas introduction hole 15 is connected to the groove 14 aat the region 100 b 1 side of the region 100 a; therefore, it can beseen from FIG. 10A that the region where the pressure of the gas changesat the vicinity of the boundary is small. Therefore, the region wherethe intended gas pressure is realized can be large.

It can be seen from FIG. 10B that it is more favorable for the gasintroduction holes 15 to be connected to the two grooves 14 a providedwith the boundary interposed because the region where the intended gaspressure is realized can be increased further.

As described above, the temperature of the object W can be controlled bythe pressure of the gas. Therefore, the temperature of the object W canbe effectively controlled if the region where the intended gas pressureis realized can be increased. Also, the occurrence of the in-planedistribution of the temperature of the object W can be suppressed. Asdescribed above, it is favorable for the gas introduction hole 15 to beconnected to the groove 14 a (the boundary groove). It is more favorablefor the gas introduction holes 15 to be connected to the two grooves 14a provided with the boundary interposed. In the example shown in FIG.9B, two gas introduction holes 15 are provided in the region 100 a. Forexample, both of the two gas introduction holes 15 may be linked to onegas supply channel 53 (referring to FIG. 1).

When the gas introduction holes 15 are connected respectively to the twogrooves 14 a provided with the boundary interposed, the angle, between atangent line intersecting the boundary and a line connecting the centerof the gas introduction hole 15 connected to one groove 14 a and thecenter of the gas introduction hole 15 connected to the other groove 14a, where the tangent line intersects the boundary at a point closest tothe joining line, can be less than 90°. In such a case, for example, theangle can be set to be not less than 1.0° and not more than 89°,favorably not less than 2.0° and not more than 70°, and more favorablynot less than 3.0° and not more than 60°.

Thus, it is possible for the boundary grooves to be more proximal toeach other; and the region where the pressure of the gas changes can besmall. Therefore, the region where the intended gas pressure is realizedcan be large.

The angle between the boundary and the line connecting the center of thegas introduction hole 15 connected to the one groove 14 a and the centerof the gas introduction hole 15 connected to the other groove 14 a alsocan be 90°.

-   -   In such a case, the angle is not exactly 90°; for example,        differences within the manufacturing fluctuation levels are        tolerable.

Thus, by arranging the two gas introduction holes 15 at counterpositions, the gases of different pressures supplied from the two gasintroduction holes 15 compete. Therefore, the pressure in each region ismaintained more easily at the target pressure.

FIG. 11 is a schematic plan view of the ceramic dielectric substrate 11according to another embodiment. FIG. 11 is a schematic plan view of theceramic dielectric substrate 11 described in FIG. 2.

As shown in FIG. 11, multiple grooves 14 c can be further provided inthe first major surface 11 a of the ceramic dielectric substrate 11. Thewidth of the groove 14 c (the dimension in a direction substantiallyperpendicular to the extension direction of the groove) can be set to,for example, not less than 0.1 mm and not more than 1 mm. The depth (thedimension in the Z-direction) of the groove 14 c can be set to, forexample, not less than 50 μm and not more than 150 μm.

In the example, at least one groove 14 c is provided in each of theregions 101, 102, and 104. The groove 14 c connects the multiple grooves14 a and 14 b provided in one region. Therefore, the gas that issupplied to the groove 14 a to which the gas introduction hole 15 isconnected flows along the groove 14 a and is supplied to the grooves 14b and the other grooves 14 a via the groove 14 c. By providing thegroove 14 c, the flow of the gas can be smooth; therefore, even withoutsealing rings, the occurrence of a pressure distribution in the regioncan be suppressed. Also, the gas can be supplied to the grooves 14 b andthe other grooves 14 a via the groove 14 c even when the top portions ofthe dots 13 wear and the gap between the object W and the first majorsurface 11 a becomes narrow.

The groove 14 c is disposed to link the grooves 14 a and the grooves 14b. For example, the groove 14 c can extend in a direction crossing thegrooves 14 a and 14 b.

For example, as shown in FIG. 11, multiple grooves 14 c can be providedon a line passing through the center of the ceramic dielectric substrate11. It is not always necessary to provide the multiple grooves 14 c on aline passing through the center of the ceramic dielectric substrate 11.Although grooves 14 c having linear configurations are illustrated, aslong as the grooves 14 c can link the grooves 14 a and the grooves 14 b,the grooves 14 c can have curved configurations, or portions havinglinear configurations and portions having curved configurations. Thenumber, the arrangement, the configurations, etc., of the multiplegrooves 14 c can be modified as appropriate according to the size of theobject W, the required specification of the temperature distribution ofthe object W, etc. For example, the number, the arrangement, theconfigurations, etc., of the multiple grooves 14 c can be determined asappropriate by performing experiments and/or simulations.

In an aspect of the invention in which the sealing ring is not provided,a contrivance is made to increase the responsiveness of the gas pressureinside the region. As an example, the gas pressure inside the region canbe effectively controlled by providing the groove 14 c linking thegrooves 14 a and the grooves 14 b.

Because the gap between the first major surface 11 a and the object Whas the height of the dots 13, the gas that is supplied to the groove 14a to which the gas introduction hole 15 is connected is supplied to thegrooves 14 b and the other grooves 14 a via the gap. However, when thetop portions of the dots 13 wear and the gap between the object W andthe first major surface 11 a becomes narrow, there is a risk that theflow of the gas inside each region may be obstructed; and a pressuredistribution may occur. By providing the groove 14 c, the gas can besupplied to the grooves 14 b and/or the other grooves 14 a via thegroove 14 c even when the top portions of the dots 13 wear and the gapbetween the object W and the first major surface 11 a becomes narrow.Therefore, the time until the pressure inside the region reaches theprescribed pressure can be shortened drastically; and the occurrence ofthe pressure distribution inside the region can be suppressed.

As shown in FIG. 11, at least two gas introduction holes 15 (first gasintroduction hole) configured to supply the gas can be provided in theregion 101 (first region), that is, the groove 14 a (first boundarygroove) extending along the boundary 102 a, which is provided in themost vicinity of the boundary 102 a (first boundary) between the region101 and the region 102 (second region).

Recently, a high density of the semiconductor integrated circuit isfurther increased, and a plasma density is also increased in order torealize further fine processing. When a hole diameter of the gasintroduction hole 15 is made small to suppress arching under the highdensity plasma, individual gas introduction holes may have an individualdifference due to manufacturing variation or the like. According to theembodiment, the effect of hole size variation of the individual gasintroduction holes can be suppressed, and a prescribed amount of gas canbe certainly supplied to the groove 14 a extending along the boundary102 a.

As shown in FIG. 11, at least two gas introduction holes 15 (second gasintroduction hole) configured to supply the gas can be provided in theregion 102, that is, the groove 14 a (second boundary groove) extendingalong the boundary 102 a, which is provided in the most vicinity of theboundary 102 a. In the example shown in FIG. 10, three gas introductionholes are provided.

In this way, as well as the previous description, the effect of holesize variation of the individual gas introduction holes can besuppressed, and a gas can be certainly supplied to the groove 14 aextending along the boundary 102 a.

Effects of the groove 14 c will now be described further.

FIG. 12A is a schematic plan view for illustrating the arrangement ofthe grooves 14 according to a comparative example.

In FIG. 12A, the multiple grooves 14 are provided in the front surfaceof a substrate 110. The multiple grooves 14 have ring configurations andare provided at uniform spacing in concentric configurations with acenter 110 a of the substrate 110 as the center. The groove 14 c is notprovided in FIG. 12A.

FIG. 12B is a schematic plan view for illustrating the grooves 14 c andthe arrangement of the grooves 14.

In FIG. 12B, the multiple grooves 14 are provided; and the multiplegrooves 14 c are provided to link at least a portion of the multiplegrooves 14 to each other. In the example, the grooves 14 c are providedon lines passing through the center 110 a of the substrate 110. Themultiple grooves 14 are connected to each other by the grooves 14 c.

FIG. 13 is a graph for illustrating the pressure change at the center110 a of the substrate 110. FIG. 13 is a graph of the pressure change atthe center 110 a of the substrate 110 determined by simulation. In thesimulation, the object W is supported by the dots 13 above the substrate110.

E in FIG. 13 is the case where the multiple grooves 14 illustrated inFIG. 12A are provided.

F in FIG. 13 is the case where the multiple grooves 14 c and themultiple grooves 14 illustrated in FIG. 12B are provided.

It can be seen from FIG. 13 that the pressure in the case illustrated inFIG. 12A (the case of E) could increase only to 95% of the prescribedpressure (20 Torr). This means that a pressure distribution may occurinside the region.

The pressure in the case illustrated in FIG. 12B (the case of F) couldincrease to the prescribed pressure (20 Torr). This means that theoccurrence of the pressure distribution inside the region can besuppressed.

Also, a time T1 necessary for increasing to the prescribed pressure inthe case of F was shorter than a time T2 necessary for increasing to 95%of the prescribed pressure in the case of E. This means that the timeuntil the pressure inside the region reaches the prescribed pressure canbe shortened drastically, that is, the responsiveness of the gas controland even the temperature control can be increased.

As described above, it is favorable for the gas introduction hole 15 tobe connected to at least one of the two grooves 14 a provided with theboundaries 101 a to 103 a interposed.

For example, as illustrated in FIG. 11, for the regions 101, 102, and104 which are inward in the first major surface 11 a, the gasintroduction hole 15 can be connected to the outermost groove 14 a ineach region. In the region 103 which is the outermost region of thefirst major surface 11 a, the gas introduction hole 15 can be connectedto the innermost groove 14 a.

The number, the arrangement, etc., of the gas introduction holes 15provided in each region can be modified as appropriate according to thesize of the object W, the required specification of the temperaturedistribution of the object W, etc. For example, as illustrated in FIG.11, three gas introduction holes 15 can be provided at uniform spacingin one region. In such a case, at least one of the multiple gasintroduction holes 15 provided in the region 103 and the gasintroduction hole 15 provided in the region 102 can be provided on aline passing through the center of the first major surface 11 a.

Although the case is described above where the region where the pressureof the gas changes at the vicinity of the boundary is reduced,considering the supply of the gas to the grooves 14 a and 14 c providedin the regions, it is favorable for the gas introduction hole 15 to beprovided at a position where the groove 14 a and the groove 14 c crossor at the vicinity of such a position. For example, when projected ontoa plane perpendicular to the Z-direction, at least a portion of the gasintroduction hole 15 can overlap at least one of the groove 14 a or thegroove 14 c at the portion where the groove 14 a and the groove 14 c areconnected. Thus, it is easy to cause the gas supplied to the groove 14 ato outflow toward the groove 14 c. Therefore, it is easy to obtain theeffects of the groove 14 c described above.

FIGS. 14A to 14C are schematic views for illustrating a form of thegroove 14 c.

FIG. 14B is an enlarged view of portion E of FIG. 14A.

FIG. 14C is an enlarged view of portion F of FIG. 14A.

As shown in FIG. 14B, for example, the groove 14 c can be provided tooverlap a line drawn from the center of the ceramic dielectric substrate11 toward the outer perimeter. In such a case, the angle between thegroove 14 c and the tangent of the groove 14 a can be 90° at the portionwhere the groove 14 a and the groove 14 c are connected.

Also, as shown in FIG. 14C, for example, the groove 14 c may not overlapa line drawn from the center of the ceramic dielectric substrate 11toward the outer perimeter. In such a case, the angle between the groove14 c and the tangent of the groove 14 a is not 90° at the portion wherethe groove 14 a and the groove 14 c are connected.

FIG. 15 is a schematic plan view of the ceramic dielectric substrate 11according to another embodiment.

In the cases illustrated in FIG. 11, the first major surface 11 a issubdivided into the multiple regions 101 to 104 having concentriccircular configurations. Conversely, in the case illustrated in FIG. 15,the first major surface 11 a is subdivided into multiple regions 105which closely contact each other. The multiple regions 105 can bearranged with each other. Although the exterior configurations of themultiple regions 105 are not particularly limited, it is favorable touse configurations which can be in close contact with each other. Forexample, the multiple regions 105 can be polygons such as triangles,quadrilaterals, etc. The exterior configuration of the region 105illustrated in FIG. 15 is a regular hexagon. The exteriorconfigurations, the number, the arrangement, etc., of the multipleregions 105 can be modified as appropriate according to the size of theobject W, the required specification of the temperature distribution ofthe object W, etc. For example, the exterior configurations, the number,the arrangement, etc., of the multiple regions 105 can be determined asappropriate by performing experiments and/or simulations.

The grooves 14 a are provided along a boundary 105 a of the region 105.The grooves 14 a are provided with the boundary 105 a interposed. Atleast one groove 14 b is provided inside the region 105. The groove 14 bcan be provided concentrically with the groove 14 a. The number, thepositions, etc., of the grooves 14 b provided in one region can bemodified as appropriate according to the size of the object W, therequired specification of the temperature distribution of the object W,etc. For example, the number, the positions, etc., of the grooves 14 bprovided in one region can be determined as appropriate by performingexperiments and/or simulations.

Otherwise, the groove 14 c, the gas introduction hole 15, the dot 13,the lift pin hole 16, the outer seal 17, etc., can be provided similarlyto those described above.

Processing Apparatus

FIG. 16 is a schematic view for illustrating a processing apparatus 200according to the embodiment.

As shown in FIG. 16, the electrostatic chuck 1, the power supply 210, amedium supplier 220, and a supplier 230 can be provided in theprocessing apparatus 200.

The power supply 210 is electrically connected to the electrode 12provided in the electrostatic chuck 1. The power supply 210 can be, forexample, a direct current power supply. The power supply 210 applies aprescribed voltage to the electrode 12. A switch that switches betweenthe application of the voltage and the cutoff of the application of thevoltage also can be provided in the power supply 210.

The medium supplier 220 is connected to the input channel 51 and theoutput channel 52. For example, the medium supplier 220 can supply aliquid used as a cooling medium or a heat-retaining medium.

The medium supplier 220 includes, for example, a container 221, acontrol valve 222, and a discharger 223.

For example, the container 221 can be a tank containing the liquid,factory piping, etc. A cooling apparatus and/or a heating apparatus thatcontrols the temperature of the liquid can be provided in the container221. A pump for supplying the liquid, etc., also can be included in thecontainer 221.

The control valve 222 is connected between the input channel 51 and thecontainer 221. The control valve 222 can control at least one of theflow rate or the pressure of the liquid. The control valve 222 also maybe able to switch between the supply of the liquid and the cutoff of thesupply of the liquid.

The discharger 223 is connected to the output channel 52. The discharger223 can be a tank, a drain pipe, etc., recovering the liquid dischargedfrom the output channel 52. The discharger 223 is not always necessary;and the liquid that is discharged from the output channel 52 may besupplied to the container 221. Thus, resource conservation can berealized by circulating the cooling medium or the heat-retaining medium.

The supplier 230 includes a gas supplier 231 and a gas controller 232.

The gas supplier 231 can be a high-pressure cylinder storing gas such ashelium or the like, factory piping, etc. Although a case is illustratedwhere one gas supplier 231 is provided, multiple gas suppliers 231 maybe provided.

The gas controller 232 is connected between the gas supplier 231 and themultiple gas supply channels 53. The gas controller 232 can control atleast one of the flow rate or the pressure of the gas. The gascontroller 232 also can further have the function of switching betweenthe supply of the gas and the cutoff of the supply of the gas. Forexample, the gas controller 232 can be a mass flow controller, a massflow meter, etc.

As shown in FIG. 16, multiple gas controllers 232 can be provided. Forexample, the gas controllers 232 can be provided respectively for themultiple regions 101 to 104. Thus, the control of the supplied gas canbe performed for each of the multiple regions 101 to 104. In such acase, the gas controllers 232 also can be provided respectively for themultiple gas supply channels 53. Thus, the control of the gas in each ofthe multiple regions 101 to 104 can be performed precisely. Although acase is illustrated where the multiple gas controllers 232 are provided,one gas controller 232 may be used as long as the supply of the gas iscontrollable independently for the multiple supply systems.

Here, a vacuum chuck, a mechanical chuck, or the like is used to holdthe object W. However, a vacuum chuck cannot be used in an environmentdepressurized from atmospheric pressure. When a mechanical chuck isused, there is a risk that the object W may be damaged and/or particlesmay occur. Therefore, for example, an electrostatic chuck is used in aprocessing apparatus used in semiconductor manufacturing processes, etc.

It is necessary to isolate the processing space of such a processingapparatus from the external environment. Therefore, the processingapparatus 200 can further include a chamber 240. For example, thechamber 240 can have an airtight structure that is capable ofmaintaining an atmosphere depressurized from atmospheric pressure.

The processing apparatus 200 also can include multiple lift pins and adrive device raising and lowering the multiple lift pins. When theobject W is received from a transfer apparatus and when the object W istransferred to the transfer apparatus, the lift pins are raised by thedrive device and protrude from the first major surface 11 a. When theobject W is received from the transfer apparatus and placed on the firstmajor surface 11 a, the lift pins are lowered by the drive device andare stored in the interior of the ceramic dielectric substrate 11.

Various apparatuses also can be provided in the processing apparatus 200according to the content of the processing. For example, a vacuum pumpthat exhausts the interior of the chamber 240, etc., can be provided. Aplasma generator that generates plasma in the interior of the chamber240 can be provided. A process gas supplier that supplies a process gasto the interior of the chamber 240 can be provided. A heater that heatsthe object W and/or the process gas also can be provided in the interiorof the chamber 240. The apparatuses that are provided in the processingapparatus 200 are not limited to those illustrated. Known technology isapplicable to the apparatuses that are provided in the processingapparatus 200; and a detailed description is therefore omitted.

As described above, the processing apparatus 200 according to theembodiment includes the electrostatic chuck 1 described above, the firstgas introduction hole (the gas introduction hole 15) provided in theelectrostatic chuck 1, and a gas controller (the gas controller 232)that can independently control the gas supplied to the second gasintroduction hole (the gas introduction hole 15). According to theprocessing apparatus 200 according to the embodiment, the pressure ofthe gas in each region can be set to be appropriate.

Hereinabove, embodiments of the invention are described. However, theinvention is not limited to these descriptions. For example, although aconfiguration in which a Coulomb force is used is illustrated as theelectrostatic chuck 1, a configuration that uses a Johnsen-Rahbek forcemay be used. Appropriate design modifications made by one skilled in theart for the embodiments described above also are within the scope of theinvention to the extent that the features of the invention are included.The components included in the embodiments described above can becombined within the limits of technical feasibility; and suchcombinations are within the scope of the invention to the extent thatthe features of the invention are included.

What is claimed is:
 1. An electrostatic chuck, comprising: a base plate;and a ceramic dielectric substrate having a first major surface andbeing provided on the base plate, the first major surface being exposedexternally, the first major surface including at least a first region,and a second region adjacent to the first region, the first region ofthe first major surface having a plurality of first grooves and at leastone first gas introduction hole provided in the first region, the atleast one first gas introduction hole being connected to at least one ofthe plurality of first grooves, the plurality of first grooves includinga first boundary groove extending along a first boundary and beingprovided to be most proximal to the first boundary, the first boundarybeing between the first region and the second region, and at least onefirst in-region groove different from the first boundary groove, thesecond region of the first major surface having a plurality of secondgrooves and at least one second gas introduction hole provided in thesecond region, the at least one second gas introduction hole beingconnected to at least one of the plurality of second grooves, theplurality of second grooves including a second boundary groove providedto be most proximal to the first boundary, the second boundary grooveextending along the first boundary, a groove end portion-end portiondistance between the first boundary groove and the second boundarygroove being shorter than a groove end portion-end portion distancebetween the first boundary groove and the first in-region grooveadjacent to the first boundary groove.
 2. The chuck according to claim1, wherein the groove end portion-end portion distance between the firstboundary groove and the second boundary groove is shorter than a grooveend portion-end portion distance between the first in-region grooves. 3.The chuck according to claim 1, wherein when projected onto a planeperpendicular to a first direction, at least a portion of the first gasintroduction hole overlaps the first boundary groove, the firstdirection being from the base plate toward the ceramic dielectricsubstrate.
 4. The chuck according to claim 1, wherein when projectedonto a plane perpendicular to a first direction, at least a portion ofthe second gas introduction hole overlaps the second boundary groove,the first direction being from the base plate toward the ceramicdielectric substrate.
 5. The chuck according to claim 1, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is less than 90°.
 6. The chuck according to claim 1, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is 90°.
 7. The chuck according to claim 1, wherein the first majorsurface includes at least the first region, the second region positionedoutward of the first region, and a third region adjacent to the secondregion and positioned outward of the second region, the plurality ofsecond grooves includes a second outer boundary groove extending along asecond boundary and being provided to be most proximal to the secondboundary, the second boundary being between the second region and thethird region, the third region has a third boundary groove extendingalong the second boundary and being provided to be adjacent to thesecond boundary, and a groove end portion-end portion distance betweenthe second outer boundary groove and the third boundary groove isgreater than the groove end portion-end portion distance between thefirst boundary groove and the second boundary groove.
 8. Anelectrostatic chuck, comprising: a base plate; and a ceramic dielectricsubstrate having a first major surface and being provided on the baseplate, the first major surface being exposed externally, the first majorsurface including at least a first region, and a second region adjacentto the first region, the first region of the first major surface havinga plurality of first grooves and at least one first gas introductionhole provided in the first region, the at least one first gasintroduction hole being connected to at least one of the plurality offirst grooves, the plurality of first grooves including a first boundarygroove extending along a first boundary and being provided to be mostproximal to the first boundary, the first boundary being between thefirst region and the second region, and at least one first in-regiongroove different from the first boundary groove, the second region ofthe first major surface having a plurality of second grooves and atleast one second gas introduction hole provided in the second region,the at least one second gas introduction hole being connected to atleast one of the plurality of second grooves, the plurality of secondgrooves including a second boundary groove extending along the firstboundary and being provided to be most proximal to the first boundary, aboundary groove occupancy ratio in a first area being larger than anin-region groove occupancy ratio in a second area, the first area havinga prescribed unit area and including the first boundary, the firstboundary groove, and the second boundary groove, the second area havingthe same configuration and the same dimensions as the first area andincluding the first in-region groove.
 9. The chuck according to claim 8,wherein a groove end portion-end portion distance between the firstboundary groove and the second boundary groove is shorter than a grooveend portion-end portion distance between the first in-region grooves.10. The chuck according to claim 8, wherein when projected onto a planeperpendicular to a first direction, at least a portion of the first gasintroduction hole overlaps the first boundary groove, the firstdirection being from the base plate toward the ceramic dielectricsubstrate.
 11. The chuck according to claim 8, wherein when projectedonto a plane perpendicular to a first direction, at least a portion ofthe second gas introduction hole overlaps the second boundary groove,the first direction being from the base plate toward the ceramicdielectric substrate.
 12. The chuck according to claim 8, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is less than 90°.
 13. The chuck according to claim 8, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is 90°.
 14. The chuck according to claim 8, wherein the first majorsurface includes at least the first region, the second region positionedoutward of the first region, and a third region adjacent to the secondregion and positioned outward of the second region, the plurality ofsecond grooves includes a second outer boundary groove extending along asecond boundary and being provided to be most proximal to the secondboundary, the second boundary being between the second region and thethird region, the third region has a third boundary groove extendingalong the second boundary and being provided to be adjacent to thesecond boundary, and a boundary groove occupancy ratio in a third areais larger than the in-region groove occupancy ratio in the first area,the third area having the prescribed unit area and including the secondboundary, the second boundary groove, and the third boundary groove. 15.An electrostatic chuck, comprising: a base plate; and a ceramicdielectric substrate having a first major surface and being provided onthe base plate, the first major surface being exposed externally, thefirst major surface including at least a first region, and a secondregion adjacent to the first region, the first region of the first majorsurface having a plurality of first grooves and at least one first gasintroduction hole provided in the first region, the at least one firstgas introduction hole being connected to at least one of the pluralityof first grooves, the plurality of first grooves including a firstboundary groove extending along a first boundary and being provided tobe most proximal to the first boundary, the first boundary being betweenthe first region and the second region, the second region of the firstmajor surface having a plurality of second grooves and at least onesecond gas introduction hole provided in the second region, the at leastone second gas introduction hole being connected to at least one of theplurality of second grooves, the plurality of second grooves including asecond boundary groove provided to be most proximal to the firstboundary, the second boundary groove extending along the first boundary,a groove end portion-end portion distance between the first boundarygroove and the second boundary groove being greater than 0 mm but notmore than 60 mm.
 16. The chuck according to claim 15, wherein the grooveend portion-end portion distance between the first boundary groove andthe second boundary groove is greater than 0 mm but not more than 20 mm.17. The chuck according to claim 15, wherein when projected onto a planeperpendicular to a first direction, at least a portion of the first gasintroduction hole overlaps the first boundary groove, the firstdirection being from the base plate toward the ceramic dielectricsubstrate.
 18. The chuck according to claim 15, wherein when projectedonto a plane perpendicular to a first direction, at least a portion ofthe second gas introduction hole overlaps the second boundary groove,the first direction being from the base plate toward the ceramicdielectric substrate.
 19. The chuck according to claim 15, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is less than 90°.
 20. The chuck according to claim 15, wherein anangle between the first boundary and a line connecting a center of thefirst gas introduction hole and a center of the second gas introductionhole is 90°.